The present invention is an improvement of Japanese Patent No. 1107913 (Number of Examined Application Published: S56-4951) invented by the same applicant, and relates to processing in a telephone terminal device which takes place when a caller hangs up before the device is activated.
For example, the telephone terminal device which was disclosed in the above-mentioned Japanese patent occasionally would not be activated after a predetermined number of ringing signals. The latter arose due to an unstable state of the telephone line resulting from abandonment of a call before engagement of the telephone line, which caused a malfunction of the so-called "toll saver" function. It may be recalled that with the toll saver function, if no messages have been recorded on the device, it is activated after four rings. If at least one message has been recorded, it is activated after two rings.
Even though the probability of such a malfunction is low, it can not be ignored. Therefore, the present invention is designed to prevent such a malfunction from ever occurring. Specifically, the present invention is directed to provide a means for activating a telephone terminal device in response to a predetermined number of ringing signals even if a new ringing signal arrives immediately after a previous call that was abandoned during ringing.